The present invention relates to communication networks, and more particularly to managing a communication link between devices on a network.
Computer networks, including digital networks, and particularly wireless networks, are vulnerable to attacks by imposters.
In the prior art, there are a number of methods for closing authenticated secure communication links between a first device and one or more other devices in an insecure network. For example, a first device may send an unauthenticated message to each other device to request closing of the communication link. If there is more than one other device, then this unauthenticated message may be broadcast to all of these other devices. Such a system is vulnerable to an attacker who sends a link closing request to these other devices, purporting to be the first device. By causing the other devices to close their links, the attacker has effectuated a denial-of-service attack.
Another method requires a device requesting a link closing to send an authenticated message. However, if only symmetric key authentication is used (as, for example, in the IEEE 802.11 standard described in [2]), and if there is more than one communication link to be closed, then there are two possible cases that could be considered. In the first case, each pair of devices shares a pairwise private key. In this case, the first device must send an individual authenticated message to each other device, each message authenticated with the appropriate pairwise private key. This is not as efficient as a broadcast. In the second case, all devices share a group private key, where a group private key is a key known to all devices in the group, but no other devices. In this case, the first device could broadcast an authenticated message to all other devices in the group. However, this system is vulnerable to an attacker who controls one of the other devices, and thus holds the group key. This attacker could broadcast a link closing request to the other devices, purporting to be the first device. Again, by causing the other devices to close their links, the attacker has effectuated a denial-of-service attack.